A wideband Lambda sensor has been made known, for example, by the German patent DE 102 16 724 C1.
For such wideband Lambda sensors the lambda characteristic curve is ascertained by means of an explicit correlation of the needed functional pumping electricity to the lambda value. The correlation results thereby from measurements taken at the exhaust gas analysis station and in the vehicle itself. The lambda characteristic curve, which is measured at the exhaust gas analysis station, is presented in a technical documentation. In place of the characteristic curve measured at the exhaust gas analysis station and put down in the technical documentation, a characteristic curve applied to the internal combustion engine is deposited in an electronic control unit of the vehicle, for example as a data set. This characteristic curve is used for the regulation of the internal combustion engine. A lambda characteristic curve obtained in such a manner is not sufficient for a precise regulation.
A lambda sensor which has a diffusion element always shows in fact a diffusion displacement, which results from the fact that different types of gas with varying masses diffuse variably fast through a diffusion element. Depending upon the exhaust mixture, this diffusion displacement leads to a significant signal deviation from a nominal characteristic curve, as it was measured at the exhaust gas analysis station. The diffusion displacement causes thereby incorrect measurements in the vehicle, which can lead to big mistakes in the Lambda regulation of the internal combustion engine.
The task which has therefore necessitated the invention is to further develop a procedure for determining the characteristic curve of a wideband sensor to the point where the diffusion displacements of the gas components, which were discussed previously, or the total lack of one or several of the gas components can be taken into account when determining the lambda value. The invention also particularly encompasses the determination of Lambda in internal combustion engines that are driven by hydrogen, ethanol or CNG (compressed natural gas).